The present invention relates to a method and apparatus for the fractional distillation of a mixture including at least two compounds with different boiling points including the steps of:
providing a column including a filling, PA1 determining a rising flow of vapor and a descending flow of liquid of the said mixture in the column. PA1 a tubular body having a top end and a bottom end at opposite ends and including a filling; PA1 a boiler in fluid communication with the bottom end, the column being characterized in that it includes a condenser extending throughout the entire length of the filling.
As is known, the term distillation indicates a chemical engineering operation in which a mixture including two or more substances with different boiling points is fractionated into individual components.
This fractionation occurs by the bringing into contact, in apparatus known as a distillation column, of a vapor phase at its dew point and a liquid at the temperature at which is starts to vapor: during this contact there is a simultaneous exchange of material and heat whereby the more volatile component transfers from the liquid phase to the vapor phase by evaporation while the less volatile component transfers from the vapour phase to the liquid phase by condensation.
In distillation operations the basic requirement to be satisfied is that of achieving the highest possible efficiency in the fractionation.
For this purpose the attempt is made, in distillation columns, to achieve the most intimate mixing possible between the liquid phase and the vapor phase, whether discontinuously in plate columns or continuously in filled columns.
In order further to increase the efficiency of fractionation and to obtain pure compounds, it is common practice to introduce the vapor phase and the liquid phase into a reflux column.
The vapor reflux is obtained by the re-evaporation of part of the liquid phase leaving the column while the liquid reflux is obtained by the condensation of all the vapor phase leaving the column and the reintroduction of a proportion of this condensate into the column itself.
It is exactly the control of the reflux quantities and the temperature of the liquid reflux phase that enables the operation of the column to be regulated to give the maximum efficiency of fractionation and very pure products.
In distillation columns universally used, the control of the working conditions in each section of the column is effected by changing the value of the reflux quantities and the temperature of the liquid reflux phase, these being the "local" working conditions dependent on the liquid-vapor equilibrium conditions in the column as a whole.
The distillation columns used in known fractionation methods thus have the disadvantage of not being very flexible and being delicate and difficult to regulate.
In filled columns in particular, each significant variation in the quality and composition of the mixture to be fractionated causes repercussions on the liquid-vapor equilibrium conditions existing in the column with the result that the products obtained may not be of the desired degree of purity.
On the other hand the use of plate columns, which are less sensitive to variations in the composition of the supply, involve a consideration increase in the dimensions of the column in order to give the same separation yield, as well as an increase in the hold-up of the liquid in the column with a related increase in the time necessary to bring the column itself to its running conditions.
The technical problem at the root of the present invention is thus to devise a method and apparatus for fractionating a mixture including at least two components with different boiling points by distillation which are simple to control and such as to ensure high efficiency in the separation of the constituents of the mixture.